It is well known in the prior art to attach flexible hoses to each other, to rigid pipes or cavities or to various rigid fittings by means of rigid nipples which are received within the ends of the hoses. Such a nipple usually has an exterior diameter substantially equal to the inner diameter of the hose and is provided with a head tapering from an exterior diameter at the free end thereof which is smaller than the inner diameter of the hose to a diameter larger than the exterior diameter of the remainder of the nipple and then back to the normal diameter of the nipple. However, it is not possible to provide a reliable fluid tight seal between the hose and the nipple solely by means of an interference fit between the hose and the head of the nipple and an attempt to do so will tend to make it impossible to insert the nipple into the hose.
Thus, in the prior art it is common practice to use a modest interference fit between the head of the nipple and the hose and to apply a hose clamp about the exterior surface of the end of the flexible hose after the nipple is inserted therein. A hose clamp by definition is adapted to apply circumferential compressive torces to the exterior surface of the hose in order to force the interior surface of the hose into sealing contact with the nipple. The hose clamp is usually applied to the hose in the region between the free end of the hose and that portion of the hose which contains the head of the nipple in order to prevent the nipple from slipping out of the hose.
Thus, a hose clamp must be capable of having its inner circumference adjusted from a diameter at least as large as the exterior diameter of the hose, for ease of application, to a diameter smaller than the exterior diameter of the hose in order to provide the circumferential compression forces necessary to produce the desired sealing and mounting effects. Such circumferential adjustment is mechanically difficult to accomplish and requires either manual dexterity in the case of spring type clamps or expensive mechanical structure in the case of rigid type clamps, such as screws, bolts or gear elements, depending on the particular hose clamp design.
More recently, it has been proposed to use hose clamps in the form of rigid collars having an internal circumference which is tapered from a diameter larger than the exterior diameter of the hose to a diameter smaller than the exterior diameter of the hose and move the collar axially of the hose in order to exert circumferential compressive forces on the exterior of the hose in an attempt to secure and seal the hose on the nipple. U.S. Pat. No. 3,361,449 issued Jan. 2, 1968 to Parro and U.S. Pat. No. 4,278,279 issued July 14, 1981 to Zimmerman are representative of this type of hose coupling mechanism.
However, according to the teaching of Parro, the entire free end portion of the hose is involved in the coupling mechanism requiring an extended taper on the nipple head and distributing the compressive forces over a large area. Thus, very high forces are required to accomplish the seal and the assembly of the hose, nipple and collar, is complicated since the hose must be forced axially into the tapered collar prior to or during the coupling action. According to the teaching of Zimmerman, the assembly of the hose, nipple and collar is facilitated by making the amount of taper of the collar relatively small, but this is done at the sacrifice of the sealing and mounting effects of the Zimmerman coupling mechanism. It will be noted that according to the teaching of Zimmerman, the frictional gripping forces exerted by his tapered coupling collar are such that the nipple may be manually pulled out of the hose without releasing the circumferential compressive force of the collar from the hose.
It is the object of this invention to overcome the above difficiencies of the prior art by providing a hose coupling mechanism which is effected by the application of compressive forces exerted axially of the hose.